Water based barrier coatings when applied to paper and paperboard contain water that has to be removed to form a continuous film. The quality of the continuous film, free of defects, is very important to achieve the optimal barrier properties.
A drying process normally removes water. The drying process is usually a thermal one (conduction, convection, radiation) in which heat is provided to the liquid to vaporize the water.
The drying condition is one of the most important factors that affect the coating performance. Quality problems such as bubbles, blisters, pinholes or cracks can occur with improper drying conditions. The production conditions must be adapted to the type of machine, coating used and the coat weight.
The cost of the drying represents a major part of the process cost, and as energy costs rise, drying efficiency becomes increasingly important.
Thus, in a time of concern over energy environment and petroleum resources, it would be beneficial to be able to coat paper using water based barrier coating without the need of heat or dryer while still having a high rate of speed of coating.